examcloud-components/src/main/java/cn/com/qmth/examcloud/web/helpers/SequenceLockHelper.java

package cn.com.qmth.examcloud.web.helpers;

import java.util.List;
import java.util.concurrent.TimeUnit;

import org.apache.commons.lang.StringUtils;
import org.assertj.core.util.Arrays;

import com.google.common.collect.Lists;

import cn.com.qmth.examcloud.commons.logging.ExamCloudLog;
import cn.com.qmth.examcloud.commons.logging.ExamCloudLogFactory;
import cn.com.qmth.examcloud.commons.util.ThreadLocalUtil;
import cn.com.qmth.examcloud.web.enums.HttpServletRequestAttribute;
import cn.com.qmth.examcloud.web.exception.SequenceLockException;
import cn.com.qmth.examcloud.web.interceptor.SeqlockInterceptor;
import cn.com.qmth.examcloud.web.redis.RedisClient;
import cn.com.qmth.examcloud.web.support.ServletUtil;
import cn.com.qmth.examcloud.web.support.SpringContextHolder;

/**
 * 并发顺序锁
 *
 * @author WANGWEI
 * @date 2019年2月22日
 * @Copyright (c) 2018-2020 WANGWEI [QQ:522080330] All Rights Reserved.
 */
public class SequenceLockHelper {

	private static final ExamCloudLog LOG = ExamCloudLogFactory.getLog(SequenceLockHelper.class);

	private static final String LOCK_PREFIX = "$_LOCK_C:";

	private static RedisClient redisClient;

	private static RedisClient getRedisClient() {
		if (null == redisClient) {
			redisClient = SpringContextHolder.getBean(RedisClient.class);
		}

		return redisClient;
	}

	/**
	 * 获取顺序请求锁<br>
	 * 
	 * @param args
	 * @throws SequenceLockException
	 *             获取锁失败时抛出异常
	 */
	public static void getLock(Object... args) throws SequenceLockException {

		String key = LOCK_PREFIX + StringUtils.join(Arrays.asList(args), "_");

		int timeout = 60 * 2;

		if (getRedisClient().setIfAbsent(key, ThreadLocalUtil.getTraceId(), timeout)) {
			if (LOG.isDebugEnabled()) {
				LOG.debug("locked");
			}
			@SuppressWarnings("unchecked")
			List<String> keyList = (List<String>) ServletUtil.getRequest()
					.getAttribute(HttpServletRequestAttribute.$_CUSTOM_SEQUENCE_LOCK.name());
			if (null == keyList) {
				keyList = Lists.newArrayList();
			}
			keyList.add(key);
			ServletUtil.getRequest().setAttribute(
					HttpServletRequestAttribute.$_CUSTOM_SEQUENCE_LOCK.name(), keyList);
		} else {
			Long expire = getRedisClient().getExpire(key, TimeUnit.SECONDS);
			if (null == expire || expire > timeout) {
				getRedisClient().delete(key);
			}

			throw new SequenceLockException("请求等待,请稍后重试!");
		}
	}
	

	/**
	 * 释放锁<br>
	 * 接口调用不要调用此方法释放锁，此锁会在拦截器<{@link SeqlockInterceptor}中释放.
	 *
	 * @author WANGWEI
	 * @param args
	 */
	public static void releaseLock(Object... args) {
		String key = LOCK_PREFIX + StringUtils.join(Arrays.asList(args), "_");
		getRedisClient().expire((String) key, 100, TimeUnit.MILLISECONDS);
		@SuppressWarnings("unchecked")
		List<String> keyList = (List<String>) ServletUtil.getRequest()
				.getAttribute(HttpServletRequestAttribute.$_CUSTOM_SEQUENCE_LOCK.name());
		if (null != keyList) {
			if (keyList.contains(key)) {
				keyList.remove(key);
			}
		}
	}
	
	   /**
     * 获取顺序请求锁<br>
     * 
     * @param args
     * @throws SequenceLockException
     *             获取锁失败时抛出异常
     */
    public static void getLockSimple(Object... args) throws SequenceLockException {

        String key = LOCK_PREFIX + StringUtils.join(Arrays.asList(args), "_");

        int timeout = 60 * 2;

        if (!getRedisClient().setIfAbsent(key, ThreadLocalUtil.getTraceId(), timeout)) {
            Long expire = getRedisClient().getExpire(key, TimeUnit.SECONDS);
            if (null == expire || expire > timeout) {
                getRedisClient().delete(key);
            }

            throw new SequenceLockException("请求等待,请稍后重试!");
        }
    }
    
    /**
     * 释放锁<br>
     * 接口调用不要调用此方法释放锁，此锁会在拦截器<{@link SeqlockInterceptor}中释放.
     *
     * @author WANGWEI
     * @param args
     */
    public static void releaseLockSimple(Object... args) {
        String key = LOCK_PREFIX + StringUtils.join(Arrays.asList(args), "_");
        getRedisClient().delete(key);
    }

}